Ulmus 'New Horizon'

Elm cultivar

Ulmus 'New Horizon' is an American hybrid cultivar raised by the Wisconsin Alumni Research Foundation (WARF), from a crossing of the Japanese Elm clone W43 8 = 'Reseda' (female parent) with Siberian Elm clone W426 grown from seed collected from a street tree at Yankton, South Dakota. As selection 'W917' it is a sibling of 'Rebona' (selection 'W916'). Tested in the US National Elm Trial coordinated by Colorado State University, 'New Horizon' averaged a survival rate of 74% after 10 years. 'New Horizon' was patented in the US in 1994, while in Europe, it is marketed as one of the 'Resista' elms protected under EU breeders' rights (EU council decision 2100/94).

Unlike its elder stablemate 'Sapporo Autumn Gold', 'New Horizon' initially has a compact, pyramidal form, with comparatively dense foliage comprising glabrous, dark green, elliptical leaves < 12 cm long by 7 cm broad, occasionally without the asymmetric bases typical of the genus. The perfect, apetalous wind pollinated flowers appear in March, followed by the seeds in April; flowering, and consequent fruiting, is sparse, in common with its female parent Japanese Elm, and usually begins when the tree is aged 8 years. The tree's growth habit is unusual; in an assessment at U C Davis as part of the National Elm Trial, its stem diameter increased faster than any other of the 15 cultivars, but increase in height, averaging 0.9 m per annum, made it one of the slowest growing, vertically. In commerce in the US, the tree is occasionally propagated by grafting onto an Ulmus pumila rootstock, rather than simply rooting cuttings as normally practiced in North America and Europe.

'New Horizon' was found hosting the endangered White letter Hairstreak at the Vauxhall Pleasure Gardens, London, in 2017; this is the first recorded instance of the butterfly breeding on the cultivar in the UK.

Bickelhaupt Arboretum, US. Acc. no. 01–008
Chicago Botanic Garden, US. 3 trees, no other details available. Morton Arboretum, US. Acc. no. 271–2008.

Arboretum de la Petite Loiterie , Monthodon, France. No details available. Botanischer Garten Marburg , Marburg, Germany. No details available. Brighton & Hove City Council, UK. NCCPG Elm Collection. Planted frequently as a street tree. Grange Farm Arboretum, Sutton St James, Spalding, Lincolnshire, UK. Acc. no. not known. Great Fontley Farm, Fareham, UK. Butterfly Conservation elm trials plantation, one standard planted 2007. Royal Botanic Gardens, Kew, UK. Acc. no. not known. Royal Horticultural Society Gardens, Wisley, UK. No details available. Sir Harold Hillier Gardens, Romsey, UK. Acc. no. 2004.0177

Carlton Plants, LLC , Dayton, Oregon, US. Charles J. Fiore Nursery , Prairie View, Illinois, US. J. Frank Schmidt & Son , Boring, Oregon, US. Johnson's Nursery , Menomonee Falls, Wisconsin, US.

Arbor Boomkwekerijen nv , Belgium. Clasen & Co Baumschulen GmbH, D Rellingen, Germany. Eisele GmbH, , Darmstadt, Germany. Hillier Nurseries , Ampfield, Hampshire, UK. Noordplant Glimmen, Netherlands. Van Den Berk (UK) Ltd., , London, UK
Vicq Arbor pépinières SA,, Vicq, France.